推 Desperato : 推 10/02 12:53
推 QQLeopard : 謝謝 10/02 23:47
※ 引述《QQLeopard (QQ)》之銘言：
: 2.
: https://i.imgur.com/gDd3Rod.jpg
: 有請神人求解
2.
x = √[x - 1/x] + √[1 - 1/x]
=> 1 - 1/x = √[x - 1/x] - √[1 - 1/x] ， x =/= 1
=> x + 1 - 1/x = 2√[x - 1/x]
u = √[x - 1/x]
=> u^2 + 1 = 2u
=> u = 1, 1
=> x - 1/x = 1
=> x^2 - x - 1 = 0
=> x = (1/2)[1 + √5] (負不合)
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